The present invention relates to a process for controlling the reactivity of isocyanate formulations by selection of a chain extender having the desired effect upon isocyanate reactivity and to a process for producing relatively stable isocyanate formulations containing activated chain extenders.
The use of isocyanate formulations to produce urethanes for a wide variety of applications is known. One of the additives that is frequently included in such isocyanate formulations is a chain extender.
The most commonly used chain extenders are diols and primary amines. However, processing difficulties are encountered with each of these types of chain extenders. Diol chain extenders react so slowly with an isocyanate that, in the absence of a catalyst, the time required to complete the reaction is commercially impractical. Primary amines, on the other hand, react much too quickly with isocyanates.
It would therefore be desirable to develop a chain extender having an isocyanate reactivity greater than that of diols but less than that of primary amines.